A disposable lancet designed for puncturing the skin of a patient's finger and enabling the taking of a blood sample is known from U.S. Pat. No. 4,889,117. The lancet is made of a long and stiff shank which exhibits on one of its ends a puncturing tip in the shape of a subcutaneous needle. At the other end the shank is joined with a capsule. The shank is slidably mounted along the entire length in a sleeve which is partially located in the capsule. A spring is located between the sleeve and the bottom of the capsule. By holding the sleeve opening against the patient's finger and pressing the capsule, the sleeve is caused to overcome the action of the spring and move toward the bottom of the capsule by a set distance sufficient to puncture the skin of the patient's finger with the puncturing tip mounted on the shank. After the lancet is used the puncturing tip retreats completely into the sleeve and the capsule element protruding inside it makes it impossible to reuse the lancet.
A finger puncturing device made up of a sleeve inside which a spring is mounted by one end is also known from the Polish disclosure document no. P.293343. On the other end of the spring, a piston with a puncturing tip is slidably mounted in the sleeve and supported by the trigger catch. After pressing the trigger, the catch releases the piston equipped with the puncturing tip and the decompressing spring causes the piston to hit the bottom of the sleeve, and the puncturing tip passing through the hole in the bottom of the sleeve punctures the patient's finger. After that the spring returns to the rest position, in which the puncturing tip is completely hidden inside the sleeve.